Biphase Co@C core-shell catalysts for efficient Fenton-like catalysis.

Area of Science:

• Materials Science
• Environmental Chemistry
• Catalysis

Background:

• Cobalt nanoparticles (Co NPs) are crucial in Fenton-like systems for pollutant oxidation.
• The specific contributions of different cobalt phases are often overlooked in catalyst design.
• Efficient degradation of refractory organic contaminants in water remains a significant environmental challenge.

Purpose of the Study:

• To synthesize a biphase Co@C core-shell catalyst using an electrochemical method.
• To investigate the catalytic performance of the biphase Co@C catalyst in degrading organic pollutants.
• To elucidate the synergistic catalytic mechanisms and reactive oxygen species involved in pollutant degradation.

Main Methods:

• Electrochemical co-reduction of CaCO3 and Co3O4 in molten carbonate at 450°C to synthesize biphase Co@C.
• Catalytic oxidation of diethyl phthalate (DEP) using the synthesized catalyst.
• Density functional theory (DFT) calculations, radical quenching experiments, and electron paramagnetic resonance (EPR) tests.

Main Results:

• The biphase Co@C catalyst exhibited excellent catalytic oxidation performance for DEP, with a high turnover frequency (28.14 min⁻¹) and low dosage (4 mg L⁻¹).
• DFT calculations confirmed synergistic effects enhancing peroxide bond breaking and electron transfer for pollutant activation.
• Multiple reactive species (SO₄•⁻, •OH, O₂•⁻, ¹O₂) were identified as co-degrading DEP, leading to 100% removal of DEP, SMX, and 2,4-DCP in various water matrices.

Conclusions:

• Electrochemical synthesis at lower temperatures (450°C) successfully produced biphase Co@C (FCC and HCP structures).
• The biphase Co@C catalyst demonstrates superior efficiency in degrading refractory organic contaminants through synergistic catalytic effects.
• This study presents a novel electrochemical approach to tune catalyst phases for enhanced catalytic activity in environmental remediation.